JP3486465B2 - Visual display device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a visual display device,
In particular, a visual display device comprising a two-dimensional image display element for displaying an observation image and an eyepiece optical system for enlarging and projecting an image of this display element in the air, and having a compact overall size, The present invention relates to a visual display device in which the decrease in the light amount is small, and the off-axis aberration is well corrected in a wide angle of view.

[0002]

2. Description of the Related Art Conventionally, visual display devices whose optical system configurations are shown in FIGS. 34 to 36 have been disclosed in USP 4,269,47.
6 (FIG. 34), USP 4,874,214 (FIG. 35),
USP 4,969,724, USP 5,000,544
(FIG. 36) and the like.

The visual display device proposed in the prior art has three problems. The first problem is USP 4,874,214 and USP 4,969,7.
With the configuration of the visual display device proposed in No. 24 and USP 5,000,544, it is difficult to reduce the overall size. The second problem is USP
4,874,214 and USP 4,969,724,
Since two semi-transmissive surfaces are arranged on the visual display device, 2
That is, the amount of light emitted from the three-dimensional image display element and reaching the observer's pupil is reduced. Further, there is also a problem that the amount of light reaching the observer's pupil from the outside world decreases. In order to observe a bright electronic image and an external image at the same time, a configuration such as USP 5,000,544 is required, but in USP 5,000,544, the range in which the observer can observe is extremely limited.
Further, with the configuration of USP 4,269,476, since only one semi-transmissive surface is included, the observer can observe a bright external image. However, in the optical path from the two-dimensional image display element to the observer's pupil, the light flux acts as a semi-transmissive surface.
The electronic image will be dark because it will be repeatedly received. The third problem is USP 4,874,214 and US
With the visual display device proposed by P4,969,724 and USP 5,000,544, it is difficult to provide the observer with a clear observation image with a wide observation angle of view and less off-axis aberrations. .

The above three problems of the prior art will be described in detail below. FIG. 34 shows USP 4,269,476.
FIG. 35 shows a partial configuration diagram of the visual display device of FIG.
4,874,214 is a block diagram of the visual display device, and FIG. 36 is a block diagram of the visual display device of USP 5,000,544. Those of USP 4,969,724 are
Because it has a configuration similar to USP 4,874,214,
See USP 4,874,214 below
It also applies to the case of 4,969,724.

In FIG. 34, the semi-transmissive plane is 11, the reflective concave surface is 12, the observer's pupil position is 13, the prism including the semi-transmissive plane 11 and the reflective concave surface 12 is 14, and the observer is observing the front. Let Z ₁ be the visual axis of.

In FIG. 35, the two-dimensional image display device is
1. The semi-transmissive plane and the semi-transmissive curved surface of the optical elements constituting the eyepiece optical system are 22 and 23, the pupil position of the observer is 24, and the visual axis of the observer is Z ₁ .

In FIG. 36, the two-dimensional image display device is
1. The prisms and the semi-transmissive curved surfaces of the optical elements constituting the eyepiece optical system are 32 and 36, the cylindrical and convex surfaces of the prism refracting surfaces are 33 and 34, the reflecting planes of the prisms are 35, and the observer's pupil position is 37 and the observer's visual axis is Z ₁ .

First, the size reduction of the visual display device, which is the first problem of the prior art, will be described. First, USP
4, 874, 214 (FIG. 35) will be described. In order to reduce the size of the visual display device, the semi-transparent plane 2
It is necessary to shorten the focal length of the eyepiece optical system composed of 2 and the semi-transmissive curved surface 23 so that the two-dimensional image display element 21 approaches the semi-transmissive plane 22. However, in order to make such a configuration, it is necessary to increase the power of the semi-transmissive curved surface 23, which not only causes deterioration of off-axis aberrations such as field curvature and coma, but also It also causes a reduction in the distance between the transmission curved surface 23 and the observer's pupil 24.
In order to avoid the deterioration of the off-axis aberration, there is a method of increasing the power of the semi-transmissive curved surface 23 while reducing the amount of eccentricity with respect to the visual axis Z ₁ of the observer.
It is necessary to increase the inclination of the semi-transmissive plane 22 with respect to the observer's visual axis Z _1, and a part of the semi-transmissive plane 22 may come into contact with the face of the observer.

Next, USP 5,000,544 (see FIG. 3)
6) will be described. In order to reduce the size of the visual display device, it is necessary to increase the power of the semi-transmissive curved surface 36 and the convex surface 34 of the refractive surface of the prism 32 to shorten the synthetic focal length of the eyepiece optical system. As did
This is not preferable because it causes deterioration of off-axis aberrations and shortens eye relief. There is also a method of increasing the power of the semi-transmissive curved surface 36 to reduce the amount of eccentricity with respect to the visual axis Z ₁ of the observer in order to avoid the deterioration of off-axis aberrations. Since the prism 32 must be arranged at a position close to the observer's face direction, the prism 32 may come into contact with the observer's eyelid or forehead. That is, USP 4,874,214 and USP
With the configuration of 5,000,544 visual display devices,
It is difficult to reduce the size.

Next, the decrease of the light quantity due to the semi-transmissive surface, which is the second problem, will be described. First, USP 4,26
9, 476 (FIG. 34) will be described. USP4,2
In 69 and 476, the luminous flux that transmits the external image to the observer's pupil passes through the semi-transmissive plane 11 only once, so that the decrease in the light amount of the external image hardly poses a problem. However, the light flux that transmits the electronic image to the observer's pupil passes through the semi-transmissive plane 11, is reflected by the reflective concave surface 12, and then returns to the semi-transmissive plane 11 again to receive the reflective action and the Pupil 13
To reach. That is, the light flux that transmits the electronic image is subjected to the action of the semi-transmissive plane 11 twice, and the decrease in the light amount cannot be avoided.

Next, USP 4,874,214 (see FIG. 3)
5) will be described. In order to prevent a decrease in the amount of light reaching the observer's pupil, for example, the semi-transparent plane 22 is set to the observer's visual axis Z.
_It may be moved to a position higher than ₁ and used as a reflection plane. In order to make such a configuration, it is necessary to increase the amount of eccentricity of the semi-transparent curved surface 23 with respect to the observer's visual axis Z ₁ .
However, it is difficult to arrange the reflection plane so as not to block the light flux reaching the observer's pupil from the front, and it is inevitable to reduce the angle of view that the observer can observe. Further, there is also a problem that off-axis aberrations such as field curvature and coma are worsened by increasing the amount of decentering of the semi-transparent curved surface 23 with respect to the observer's visual axis Z ₁ .

Finally, USP 5,000,544 (see FIG.
6) will be described. In the case of USP 5,000,544, since there is only one semi-transmissive surface, it is possible to obtain a bright electronic image and ambient light, and the decrease in the amount of light reaching the observer's pupil does not pose any particular problem. However, the observable range becomes very narrow due to the problem of the space in which the reflection plane 35 is arranged. In order to widen the observable range of the observer, the reflection plane 35 of the prism 32 has to be enlarged to the front of the pupil 37 of the observer, so the reflection plane 35 needs to be replaced with a semi-transmission plane. Then, two semi-transmissive surfaces are included in the eyepiece optical system, which causes a problem of reduction in the amount of light reaching the observer's pupil.

That is, in the structure of USP 4,269,476, the decrease of the light quantity of the electronic image becomes a problem,
In the configuration of 4,874,214, there is a problem that the light amount of the electronic image and the external image is reduced. Also, USP 5,000,54
In No. 4, the observable range of the observer is narrowed to avoid a decrease in the amount of light reaching the observer's pupil. However, when the observable range is widened, the decrease in the amount of light inevitably becomes a problem. Will end up.

Finally, the third problem, that is, the deterioration of the off-axis aberration at a wide viewing angle, will be described. First, USP
4, 874, 214 (FIG. 35) will be described. When an image with a wide viewing angle is provided to the observer, the spread of the chief ray reaching the semi-transmissive curved surface 23 becomes large, so that the diameter of the light beam reflected by the semi-transmissive curved surface 23 becomes large and a large field curvature is generated. Will occur. Further, when the observation angle of view is widened, a large pupil diameter is required to observe the observation image in every corner, but this is because the diameter of the off-axis light flux reflected by the semi-transmissive curved surface 23 becomes large, so that coma aberration is increased. Cause worse.

In USP 5,000,544 (FIG. 36) as well, in the same manner as USP 4,874,214, it is attempted to provide an observer with an observation image with a wide angle of view and a large pupil diameter.
It is inevitable that a large amount of field curvature and coma will occur on the semi-transparent curved surface 36. That is, USP 4,874,2
It is difficult to obtain an observation image with a wide angle of view and a small off-axis aberration with the configuration of the visual display device of No. 14 or USP 5,000,544.

[0016]

SUMMARY OF THE INVENTION The present invention has been made in view of the problems of the prior art as described above, and an object thereof is to make the overall size compact and to reduce the amount of light in the eyepiece optical system. It is an object of the present invention to provide a visual display device with a small angle of view and a wide field angle in which off-axis aberrations are favorably corrected.

[0017]

A visual display device according to a first aspect of the present invention that achieves the above object displays an observation image.
In a visual display device including a three-dimensional image display element and an eyepiece optical system that forms an eye point for guiding the observation image to an observer's eyeball, the eyepiece optical system includes at least a first reflection surface and a second reflection surface. And the first reflecting surface is arranged so as to face the two-dimensional image display element, the second reflecting surface is arranged so as to face the eye point, and The optical axis connecting the reflecting surface and the two-dimensional image display element is arranged to intersect with the optical axis connecting the second reflecting surface and the eye point, and the first reflecting surface and the second Both reflective surfaces have positive power,
At least one shape in the reflecting surface is configured so that the power in the spherical surface is stronger than the positive power in the meridional surface and the focal length of the light beam in the spherical surface is shortened. It is characterized by.

The visual display device of the second invention comprises a two-dimensional image display element for displaying an observation image and an eyepiece optical system for forming an eye point for guiding the observation image to the observer's eyeball. In, the eyepiece optical system is a prism having at least a first reflecting surface, a second reflecting surface, a first transmitting surface and a second transmitting surface, and the prism is
The first reflection surface is arranged to face the two-dimensional image display element with the first transmission surface interposed therebetween, and the second reflection surface has the eye point disposed with the second transmission surface interposed therebetween. And an optical axis connecting the first reflecting surface and the first transmitting surface and an optical axis connecting the second reflecting surface and the second transmitting surface intersect with each other. The first reflecting surface, the second reflecting surface, and the first transmitting surface are arranged such that at least one of the first reflecting surface and the second reflecting surface has a positive power. Surface, at least one of the shapes of the second transmitting surface makes the power in the sagittal surface stronger than the positive power in the meridional surface and shortens the focal length of the light beam in the sagittal surface. It is characterized by being configured.

The visual display device of the third invention comprises a two-dimensional image display element for displaying an observation image and an eyepiece optical system for forming an eye point for guiding the observation image to an observer's eyeball. In, the eyepiece optical system has at least a first reflecting surface and a second reflecting surface, and the optical axes passing through the first reflecting surface and the second reflecting surface partially intersect each other. Arranged to form a polygon,
Both the first reflecting surface and the second reflecting surface have positive power, and at least one shape in the reflecting surface makes the power in the sagittal surface stronger than the positive power in the meridional surface. It is characterized in that the focal length of the light flux in the spherical surface is shortened.

By the way, "the optical axes intersect" in the present invention includes not only plane intersections but also three-dimensional intersections. The term "intersection" as used herein refers to a state in which the optical axes intersect with each other in a cross shape, or a state where the optical axes form a cross. Therefore, the optical axis does not include a T-shaped one as shown in FIG. In addition, this is because the present invention is based on the premise that the light amount loss is reduced and the overall size is made compact, and that the technical idea created as a means for achieving it is “intersection of optical axes”. Of course, it is rather natural that the configuration shown in FIG. 34 is excluded.

[0021]

The reason why the above structure is adopted and the operation thereof will be described below. As described above, reducing the combined focal length of the eyepiece optical system in order to reduce the overall size of the visual display device causes deterioration of off-axis aberrations and reduction of eye relief. Therefore, in the present invention, the size of the entire visual display device is reduced by considering the location where the optical elements forming the eyepiece optical system are arranged without depending on the combined focal length of the eyepiece optical system.

First, the first invention and the third invention will be described in detail with reference to FIGS. Figure 1
It is a figure which shows arrangement | positioning of the reflective surface which comprises the visual display apparatus of this invention, and FIG. 2 is a figure which shows the arrangement of the reflective surface which comprises the similar visual display apparatus of a prior art. In FIGS. 1 and 2, the two-dimensional image display element is 1, the reflection plane that first reflects the light flux emitted from the two-dimensional image display element is 2, and the light flux reflected by the reflection plane 2 is in the direction of the observer's pupil. The concave surface to be reflected is 3, the observer's pupil position is 4, the visual axis when the observer is observing the front is Z, the perpendicular of the reflecting plane 2 is Z ₁ , and the reflecting concave surface 3 and the visual axis Z are Let Z ₂ be the normal line of the reflective concave surface 3 at the intersection.

In the prior art, as shown in FIG. 2, the chief ray emitted from the two-dimensional image display element 1 is a normal line Z of the reflection plane 2.
_{It is} incident on ₁ from above and reflected downward.
Then, on the reflection concave surface 3 that reflects the light flux reflected by the reflection plane 2 toward the observer's pupil 4, the light flux reflected by the reflection plane 2 enters from above from the normal line Z ₂ of the reflection concave surface 3,
Reflect downwards. That is, in the configuration of the reflective surface in the conventional technique, the optical path of the axial chief ray from the center of the two-dimensional image display element 1 to the center of the observer's pupil 4 does not intersect in the optical path even once, and the visual display device is provided. Requires a large space.

In the present invention, the optical path of the axial chief ray from the center of the two-dimensional image display device 1 to the center of the observer's pupil 4 requires less space than the prior art. is there. In the present invention, as shown in FIG. 1, the principal ray emitted from the two-dimensional image display element 1 is the normal Z of the reflection plane 2.
_{It is} incident on ₁ from above and reflected downward.
Then, the light flux reflected by the reflection plane 2 is incident on the perpendicular Z ₂ of the reflection concave surface 3 from below and is reflected upwardly where the observer's pupil 4 is located. These two reflective surfaces 2, 3
With such an arrangement, it is possible to obtain a visual display device that requires less space without reducing the synthetic focal length of the eyepiece optical system.

When the viewing angle of view of the visual display device is widened, the pupil diameter is accordingly increased, so that a large amount of field curvature and coma are generated on the reflecting surface which constitutes the eyepiece optical system.
As described above, it becomes difficult for an observer to observe a flat and clear image. Therefore, in the present invention, by making the diameter of the light beam incident on the reflecting surface constituting the eyepiece optical system small even when the pupil diameter is wide and the pupil diameter is large,
The amount of field curvature and coma generated on the reflecting surface is reduced.

The second invention will be described in detail below with reference to FIG. FIG. 3 is a diagram showing the arrangement of the prisms 7 that form the visual display device of the present invention. In FIG. 3, the two-dimensional image display element 1 is a two-dimensional image display element 1
The light flux emitted from the first incident light enters the prism 7 at the transmitting surface 5, the light flux incident on the prism 7 reflects the first reflecting surface that is the first reflecting surface at 2, and the light flux reflected at the reflecting plane 2 is observed by the observer. When the viewer is observing the front, the reflecting concave surface that is the second reflecting surface that is reflected toward the pupil is 3, the transmitting surface through which the light beam is emitted from the prism 7 is 6, and the observer's pupil position is 4. , Z is the visual axis, and L _{CR is} the light flux consisting of the chief ray, and L _MR is the on-axis and off-axis light flux.

Of the optical elements constituting the visual display device, the reflecting concave surface 3 which has power and is eccentric with respect to the optical axis is likely to cause field curvature and coma. That is, in order to deal with a wide angle of view and a large pupil diameter, it is important to suppress the occurrence of off-axis aberrations on the reflective concave surface 3. In order for an observer to see an image with a wide angle of view, the luminous flux diameter of the chief ray bundle L _CR exiting the two-dimensional image display element 1 needs to be large, but this chief ray bundle L _CR passes through the reflection plane 2. Reflective concave surface 3
If it is incident on, a large amount of field curvature will occur. Further, in order to increase the pupil diameter as the observation angle of view becomes wider, it is necessary that each chief ray exiting the two-dimensional image display element 1 has a large numerical aperture. This causes the beam diameters of the on-axis and off-axis light beams L _{MR on} the reflecting concave surface 3 to increase, and a large amount of coma aberration also occurs on the reflecting concave surface 3.

In order to correct the above-mentioned off-axis aberration, the transmission surface 5 is arranged in the optical path connecting the two-dimensional image display element 1 and the reflection plane 2, and the space between the transmission surface 5 and the reflection plane 2 is air or more. It is important to use a glass material having a refractive index. With such a configuration, the on-axis and off-axis light fluxes L _MR are refracted by the transmitting surface 5, so that the light flux diameter when entering the reflecting concave surface 3 is reduced, and the amount of coma aberration is reduced. It becomes possible. It is also important to dispose the transmissive surface 6 in the optical path connecting the pupil 4 of the observer and the reflective concave surface 3 and to form a space between the transmissive surface 6 and the reflective concave surface 3 with a glass material having a refractive index higher than that of air. . With such a configuration, even if the beam diameter of the chief ray bundle L _CR when entering the reflecting concave surface 3 is small, the observer observes the front surface of the chief ray bundle L _CR that reaches the pupil 4 of the observer. Therefore, it has a large angle with respect to the visual axis Z when it is operating. In other words, it provides the observer with a wide viewing angle,
In addition, it is possible to suppress the amount of field curvature generated.

That is, the reflecting flat surface 2 and the reflecting concave surface 3 are arranged between the two transmitting surfaces 5 and 6, and the optical path from the transmitting surface 5 to the transmitting surface 6 is placed in a glass material having a refractive index higher than that of air. By configuring these optical elements as the prism 7, even if a light flux with a large pupil diameter is actually delivered from the two-dimensional image display element 1 to the observer's pupil 4 at a wide angle of view, the light flux is converted into a two-dimensional image. At the reflection plane 2 and the reflection concave surface 3 which have a role of reaching from the display element 1 to the observer's pupil 4, since the light flux has a small angle of view and a pupil diameter, deterioration of off-axis aberrations on the reflection surface is avoided. It becomes possible to do it.

More preferably, the transmitting surface 5 has a function of reducing the diameters of the chief ray bundle L _CR and the on-axis and off-axis bundles L _MR by providing the transmitting surface 5 with a power and a refracting surface. become. Similarly, even if the light flux diameters of the principal ray bundle L _CR and the on-axis and off-axis rays L _MR on the reflecting surface are small by making the transmitting surface 6 a refracting surface with power, it is possible for the observer to see it on the transmitting surface 6. It is possible to increase the diameters of the chief ray bundle L _CR reaching the pupil 4 and the on-axis and off-axis bundles L _MR . That is, the transmissive surfaces 5 and 6 help to correct off-axis aberrations of field curvature and coma, respectively, so that the observer can observe a clearer and flatter image.

In the above, more preferably, at least one of the above-mentioned two reflecting surfaces is a concave surface having a positive power, in order to obtain a visual display device that provides a wider viewing angle of view to the observer. It is preferable. In order to provide the observer with a wider viewing angle, it is necessary that the distance between the two-dimensional image display element 1 and the first reflecting surface 2 is sufficiently large so as not to block the light flux reaching the pupil 4 of the observer. . For this,
It is important that the front focal position of the optical system is located farther than the first reflecting surface 2, and it is necessary to consider the power distribution of the reflecting surface of the prism 7 that constitutes the eyepiece optical system. In the second invention, as already described above, the two transmission surfaces 5 and 6 forming the prism 7 play a role of mainly reducing the diameter of the light beam incident on the reflection surface. On the other hand, the prism 7
The reflecting surfaces 2 and 3 constituting the main component mainly play a role of determining the front focus position and the rear focus position of the eyepiece optical system. Therefore, when the eyepiece optical system is composed of two reflecting surfaces 2 and 3, the influence of the power distribution of the reflecting surfaces on the front and rear focal positions of the optical system will be described in detail.

The operation of the first to third inventions will be described below with reference to FIG.
This will be described in detail with reference to (a) and FIG. 4 (b). Figure 4
FIG. 4A is a diagram in which the visual display device when the eyepiece optical system is composed of a reflection plane and a reflection concave surface is replaced with a state of a decentered refraction optical system, and FIG. 4B shows the eyepiece optical system. It is the figure which replaced the state of the refractive optical system which is not eccentric with the visual display device when it comprised by two reflective concave surfaces.

In FIGS. 4 (a) and 4 (b), the two-dimensional image display device is 1, the light beam emitted from the two-dimensional image display device 1 is first reflected on the surface 2, and the light beam reflected by the reflection surface 2 is reflected. To the observer's pupil, and the observer's pupil to 4
And the front focus position (the position of the two-dimensional display element 1) is F ₀ ,
The rear focal position (the position of the observer's pupil 4) is F ₁ , the focal length of the optical system is f, the focal lengths of the first reflecting surface 2 and the second reflecting surface 3 are f ₁ and f ₂ , respectively. The focal length is ff1, the rear focal length is bf1, the first reflecting surface 2 and the second reflecting surface 3
Let d be the interval of.

Further, in FIG. 4A, the principal point of the optical system is H, and the intersection of the reflection concave surface 3 and the optical axis is O. In FIG. 4B, the principal points of the optical system are H ₁ and H. ₂ and the intersections of the reflecting concave surfaces 2 and 3 with the optical axis are O ₁ and O ₂ , respectively.

First, the case where the eyepiece optical system is composed of a reflecting flat surface and a reflecting concave surface will be described. Since the first reflecting surface 2 is a plane having no power, the principal point H of the eyepiece optical system is
Is located at the position of the reflection concave surface 3, and the focal length f ₂ of the reflection concave surface 3 determines the front focus position F ₀ and the rear focus position F ₁ of the optical system. In order to improve the telecentricity of the two-dimensional image display element 1 and to display an image with uniform brightness on the pupil 4 of the observer, two-dimensional images are formed at the focal positions F ₀ and F ₁ of the reflective concave surface 3. The image display element 1 and the observer's pupil 4 need to be located respectively.
However, when trying to obtain a visual display device that satisfies this condition, the first reflecting surface 2 is located in the middle of the front focal length ff1 of the optical system, so that the two-dimensional image display element 1 and the reflecting plane 2 are separated from each other. Since the interval becomes small, the two-dimensional image display element 1 and the reflection plane 2 block the light flux range that the observer can observe, and the observer's observable range may be reduced.

In order to widen the observable range of the observer without changing the size of the eyepiece optical system, the distance d between the reflection plane 2 and the reflection concave surface 3 is unchanged, and the reflection plane 2 and the front focus position ( The distance from the two-dimensional image display element 1 position F ₀ must be sufficiently large. For that purpose, it is necessary to locate the principal point near the reflection plane 2 and keep the front focus position F ₀ away from the first reflection surface 2. In order for the principal point to be located at a position other than the reflecting concave surface 3, the reflecting surface having positive power must be included in the eyepiece optical system in addition to the reflecting concave surface 3, and the eyepiece optical system must have two principal points. .

Therefore, a case where the eyepiece optical system is composed of two reflecting surfaces having positive power will be described. The positions of the principal points H ₁ and H ₂ of the eyepiece optical system are defined by the following equations.

H ₁ O ₁ = fd / f ₂ H ₂ O ₂ = -fd / f _{1 When the} eyepiece optical system includes only one reflecting surface having positive power, the focal length f of the reflecting concave surface 3 is f 1. ₂ was the focal length f of the eyepiece optical system. When the eyepiece optical system is composed of two reflecting surfaces having positive power, the focal length f
, The focal lengths f ₁ and f ₂ of the reflecting surfaces 2 and 3 are determined, and the distance d between the reflecting surfaces 2 and 3 is set so that the size of the eyepiece optical system does not increase.
If the equation H ₁ O ₁ <d is true, then the principal point H that determines the front focus position F _{0
Since 1} is located between the two reflecting concave surfaces, the front focus position F ₀ can be moved away from the first reflecting surface 2.

The visual display device has positive power and
Since the reflecting surfaces 2 and 3 constituting this visual display device also have positive power, the following formula is established.

F <f ₂ When both sides are multiplied by d, fd <f ₂ d fd / f ₂ <d H ₁ O ₁ <d, and the principal point H ₁ which determines the front focal point F ₀ is two reflections. Located between the concave surfaces, the two-dimensional image display element 1 and the first reflective concave surface 2 have a larger distance. As a result, the range of the light flux that can pass between the two-dimensional image display element 1 and the reflective concave surface 2 becomes large, so that the observer can be provided with an observation image with a wider field angle.

Further, by giving positive power to both of the two reflecting surfaces 2 and 3 of the prism 7 constituting the eyepiece optical system, the rear focal length bf1 is shortened and the eye relief is reduced. This is because the principal point H ₂ that determines the distance between the second reflecting surface 3 and the observer's pupil 4 has moved from the position of the second reflecting surface 3 toward the first reflecting surface 2. If sufficient eye relief cannot be secured, the visual display device will come into contact with the observer's eyelids and forehead. Therefore, in order to secure a sufficient eye relief and to make the size of the visual display device compact, it is preferable to satisfy the following conditional expression.

30 <f <100 [mm] The combined focal length f of the eyepiece optical system is 1 which is the upper limit of the above conditional expression.
When it exceeds 00, the size of the visual display device becomes too large, and when it exceeds the lower limit of 30 of the above conditional expression, sufficient eye relief cannot be secured.

Further, when the two reflecting surfaces 2 and 3 of the prism 7 constituting the eyepiece optical system are both concave surfaces having positive power, more preferably, in order to reduce the fatigue of the eyes of the observer, It is preferable to incline the second reflection surface 3 side of the two-dimensional image display element 1 from the pupil 4 side of the observer so as to be closer to the visual axis Z of the observer.

The operation will be described below with reference to FIGS. 5 and 6. In FIG. 5, the two-dimensional image display element is 1, the first transmissive surface forming the prism 7 is 5, the first reflective surface is 2, the second reflective surface is 3, and the second transmissive surface is 6. The observer's pupil position is 4, the observer's visual axis is Z, the upper off-axis light flux seen from the observer's pupil is L _UP , and the lower off-axis light flux seen from the observer's pupil is L _LOW . The on-axis light flux seen from the pupil 4 is L.

As is apparent from FIG. 5, the lower off-axis light flux L
_LOW has a shorter distance from the first reflecting surface 2 to the second reflecting surface 3 than the upper off-axis light flux L _UP, and has a longer distance from the two-dimensional image display element 1 to the first reflecting surface 2. Become. FIG. 6 shows the difference in the power distribution of the optical system received by the upper off-axis light flux L _UP and the lower off-axis light flux L _LOW . As is clear from FIG.
The front focus position F _O of the lower off-axis light flux L _LOW is located closer to the optical system than the front focus position F _O of the upper off-axis light flux L _UP (FIG. 6A shows the upper off-axis light flux L _O ). corresponding to _UP, FIG. 6 (b) corresponds to the lower off-axis light beam L _LOW.),
As a result, the lower off-axis light flux L _LOW reaching the observer's pupil 4 is not observed as if it is projecting the image at infinity, and the observer focuses the eye when observing the lower image. It will be necessary to adjust the distance closer to infinity. This is not preferable because the observer may feel tired in the eyes.

Therefore, the second reflecting surface 3 side of the two-dimensional image display element 1 is tilted so as to be closer to the observer's visual axis Z than the observer's pupil 4 side, and is moved to the position 8 in FIG. so,
The front focal position F _O of the lower off-axis light flux L _LOW is brought closer to the optical system so that the observer can observe an image at infinity even when observing the lower image, thereby reducing the eyestrain of the observer. It is preferable to adopt such a configuration.

More preferably, in order to obtain a visual display device which provides a wider viewing angle of view and a longer eye relief to the observer, of the two reflecting surfaces constituting the eyepiece optical system,
It is preferable to use at least one back mirror.
This point will be described in detail with reference to FIG. FIG. 7 is a cross-sectional view of a visual display device in which a concave mirror that first reflects a principal ray emitted from a two-dimensional image display element is a rear surface mirror, and the two-dimensional image display element is a back surface having a first reflection surface. The mirror is 9, the refracting surface of the back mirror is 10, the reflecting surface of the back mirror is 2, the concave mirror which is the second reflecting surface is 3, and the observer's pupil position is 4.

The first reflecting surface 2 is a refracting surface 1 having negative power.
By constructing the backside mirror 9 having 0, the focal length of the backside mirror 9 having the first reflecting surface 2 becomes longer than the conventional one. From the above-mentioned defining equation for determining the principal point position, this is the principal point H for determining the rear focus position of the optical system (the position of the observer's pupil 4).
₁ is brought closer to the second reflecting surface 3 so that the rear focal point position F ₁ (position of the observer's pupil 4) is located further away from the second reflecting surface 3 and the eye relief for the observer is longer. Can be provided. Further, by disposing the refracting surface 10 having a negative power between the first reflecting surface 2 and the two-dimensional image display element 1, the power of the second reflecting surface 3 is the same and the front focal position (two-dimensional image). Principal point H ₀ that determines the position of the display element 1)
Even if is at the same position as in the prior art, the front focus position F ₀ (position of the two-dimensional image display element 1) can be moved away from the optical system. As a result, the range of the light flux reaching the observer's pupil 4 is expanded, and the observer can be provided with an image with a wide angle of view.

Even when the second reflecting surface 3 is formed as a back surface mirror, it is possible to provide an observation image with a wider angle of view and a longer eye relief by the same operation as described above.

More preferably, in the first invention and the second invention, in order to provide a clear image to the observer, the two reflecting surfaces or at least one refracting surface of the rear surface mirror constituting the eyepiece optical system are provided. Among them, at least one surface, the intersection of the intersection of the optical axis and the reflection surface or the refraction surface, the radius of curvature in the plane including the normal line of the reflection surface or the refraction surface passing through the intersection point and the optical axis, It is preferable that the surface is orthogonal to this plane and has a different radius of curvature in the plane including the normal line.

Hereinafter, this action will be described with reference to FIGS. 8 and 9.
The details will be described. FIG. 8 shows that when the intersection of the axial principal ray (optical axis) connecting the center of the observer's pupil 4 with the center of the reflecting surface 2, 3 is the center of the reflecting surface, When the radius of curvature of the reflecting surface in a plane including the normal line passing through the center and the optical axis and the radius of curvature of the reflecting surface in the plane orthogonal to the plane and including the normal line are the same, It is a three-dimensional figure. FIG. 9 is a stereoscopic view of the visual display device when the radii of curvature of the first reflecting surface 2 in the respective planes are different. Hereinafter, for convenience of description, the respective planes will be defined as the meridional surface of the reflecting surface or the refracting surface and the spherical surface of the reflecting surface or the refracting surface.

Further, for the sake of convenience of explanation, among the light fluxes that exit the two-dimensional image display element 1 and reach the pupil 4 of the observer, those having a light flux component only within the spherical surface of the pupil 4 of the observer. Is defined as a luminous flux in the meridional plane, and a luminous flux component only in the meridian plane of the observer's pupil is defined as a luminous flux in the meridional plane.

FIGS. 8A and 9A show the pupil 4 of the observer.
FIG. 8 (b) and FIG.
(B) is a figure which shows a part of meridian image formed in an observer's pupil 4. In order to make it easy to see the positions where the spherical image and meridian image are formed, the light rays are transmitted from the observer's pupil 4 to the two-dimensional image display element 1.
Back ray tracing to is shown.

8 and 9, the two-dimensional image display element is 1, the first reflecting surface is 2, the second reflecting surface is 3, and the observer's pupil position is 4. When the radii of curvature in the meridional surface of the reflecting surface 2 and the spherical surface of the reflecting surface 2 are the same, the spherical image is located on the rear side of the two-dimensional image display element 1 as shown in FIG. In other words, this means that the light flux in the spherical surface exiting the two-dimensional image display element 1 forms an image on the rear side of the observer's pupil position 4. Further, as shown in FIG. 8B, the meridian image is located on the front side of the two-dimensional image display element 1. In other words, the luminous flux in the meridional plane exiting the two-dimensional image display element 1 is observed. The image is formed in front of the pupil position 4 of the person. That is, the astigmatic difference existing in the visual display device is large, and when the image observed by the observer requires high resolution, the observer may not be able to observe a sufficiently clear image.

Therefore, in order to provide a clear and high-resolution image to the observer, at least one of the two reflecting surfaces or the refracting surface of the at least one rear-view mirror constituting the eyepiece optical system is to be a surface. It is preferable that the radius of curvature be different between the meridional surface and the spherically absent surface. Figure 8
As shown in (a) and (b), the positive power received by the ocular optical system is stronger in the meridional plane than in the spherical plane, and the focal length of the luminous flux in the spherical plane is meridian. It becomes longer than the focal length of the in-plane light flux. To reduce this difference in focal length, make the positive power in the spherical surface of the reflecting surface stronger than the positive power in the meridional surface, or in the spherical surface of the refracting surface of the rear surface mirror. It is preferable that the negative power at is weaker than the negative power in the meridian plane. 9 (a) and 9 (b) show an example in which the positive power in the spherical surface of one of the reflecting surfaces constituting the visual display device is made stronger than the positive power in the meridional surface. As shown in FIGS. 9A and 9B, the astigmatic difference is reduced, and as a result, an image with high resolution can be provided to the observer.

More preferably, in the second invention, in order to provide a clearer image to the observer, at least one of the two reflecting surfaces or the two transmitting surfaces constituting the prism is light-exposed. The intersection of the axis and the reflecting or transmitting surface is taken as the intersection, and the radius of curvature in the plane containing the optical axis and the normal of the reflecting or transmitting surface passing through the intersection and the orthogonal to this plane and the above-mentioned method. It is preferable that the surface has a different radius of curvature in a plane including the line.

For convenience of explanation, each of the above planes will be defined as a meridional surface of a reflecting surface or a transmitting surface and a spherical surface. Further, among the light fluxes that have exited the two-dimensional image display element 1 and reach the observer's pupil 4, those having a light flux component only in the spherically absent surface of the observer's pupil are the light fluxes in the aspherical surface, A light beam having a light beam component only in the meridian plane of the pupil is defined as a light beam in the meridian plane.

Hereinafter, this operation will be described in detail with reference to FIG. FIG. 10 is a cross-sectional view of the visual display device when the radii of curvature of the reflecting surface and the transmitting surface of the rhythm 7 are the same in the meridional surface and in the spherical surface. In order to make it easy to see the positions where the spherical image and the meridian image are formed, the light rays are shown by backward ray tracing from the observer's pupil 4 to the two-dimensional image display element 1. In FIG. 10, the two-dimensional image display element is 1, the first transmissive surface constituting the prism 7 is 5, the first reflective surface 2, the second reflective surface 3 and the second transmissive surface 6, and the observer. The pupil position of 4 is 4, the image plane of the spherical image is I _X , and the meridian image plane is I _Y
Show as.

When the reflecting surface and the transmitting surface have the same radius of curvature in the meridional surface and in the spherical surface, as shown in FIG. 10, the image surface I _X of the spherical image is the image plane of the two-dimensional image display element 1. It is located on the rear side, in other words, the light flux in the spherical surface exiting the two-dimensional image display element 1 is imaged on the rear side of the observer's pupil position 4. On the other hand, the image plane I _Y of the meridian image is located on the front side of the two-dimensional image display element 1, which in other words,
The light flux in the meridional plane that exits the two-dimensional image display element 1 is focused on the front side of the observer's pupil position 4. That is, the astigmatic difference existing in the visual display device is large, and when the image observed by the observer requires high resolution, the observer may not be able to observe a sufficiently clear image.

Therefore, in order to provide a clear and high-resolution image to the observer, at least one of the reflecting surfaces 2 and 3 and the transmitting surfaces 5 and 6 forming the prism 7 is a reflecting surface or a transmitting surface. It is preferable that the radius of curvature be different between the meridional surface and the spherically absent surface. As mentioned above,
The positive power received by the eyepiece optical system is stronger in the light flux in the meridional plane than in the light flux in the spherical surface, and the focal length of the light flux in the spherical surface is longer than the focal length of the light flux in the meridional surface. In order to obtain a clear image with higher resolution, it is necessary to reduce this difference in focal length. For this purpose, it is important to make the power in the spherical surface of the reflecting surface or the transmitting surface stronger than the positive power in the meridional surface and shorten the focal length of the light beam in the spherical surface.

In order to utilize the above-described present invention as a visual display device having a superimposing function (a function of displaying an electronic image and an external image in an overlapping manner at the same time), two reflections constituting an eyepiece optical system are used. It is necessary that at least one of the surfaces is a semitransparent surface.

In order for the observer to simultaneously observe the front view of the outside world and the electronic image transmitted from the two-dimensional image display element 1 to the observer's pupil 4, the second image positioned in front of the observer's pupil 4 is used. The reflecting surface 3 of 1 may be replaced with a semi-transmissive surface.

In the case of the visual display device of the present invention, even if the reflective surface is replaced with a semi-transmissive surface as a constituent element, the observable angle of view and the size of the visual display device do not increase. Further, even if the visual display device has a superimpose function, only one semi-transmissive surface is included in the components of the eyepiece optical system, and the two-dimensional image display device and the outside world can be observed. Since each light flux reaching the observer's pupil is subjected to the action of the semi-transmissive surface only once, the decrease in the amount of light reaching the observer's pupil is considerably smaller than that of the conventional one. The transmissivity / reflectance ratio of the semi-transmissive surface used in the present invention is utilized in the range of 2: 8 to 8: 2.

As means for dividing such a light quantity, there are a method of dividing as an area, a method of dividing intensity,
And yet, there are ways to use both. A method of dividing by the above area is shown in FIG. In FIG.
An aluminum coating 42 is provided on a transparent substrate 41 such as glass or plastic. This aluminum coating 4
No. 2 is coated on a mesh-like mesh of several μm to 0.1 mm, and the overall (macro) reflectance and transmittance are set by the ratio of the areas of the reflecting portion and the transmitting portion without reflecting. .

Next, FIG. 12 shows means for dividing the transmitted and reflected light amounts in terms of light amount. This method is relatively easy to implement and inexpensive to fabricate. As shown in FIG. 12, a semi-transmissive thin film 43 can be coated on a transparent substrate 41 such as glass or plastic to divide the amount of light. As the semi-transmissive thin film 43, Al
Metal thin films such as (aluminum) and Cr (chrome) are common. In addition, as a dielectric multilayer film, SiO ₂ ,
A general method is to combine a number of thin films of MgF ₂ or the like.

FIG. 13 shows a method using polarization as another method of dividing the quantity of transmitted light and the quantity of reflected light. FIG.
In, a transparent substrate 41 such as glass or plastic
Is coated with a polarizing semi-transmissive thin film 44 to selectively transmit or reflect P-polarized light and S-polarized light to divide the light, and reflectivity and transmittance are determined by the ratio of P-polarized light and S-polarized light of incident light. Is set. Furthermore, it is also possible to use any combination of the above methods. There is also a method of dividing the amount of light transmitted and reflected by a holographic optical element.

[0067]

EXAMPLES Examples 1 to 10 of the eyepiece optical system used in the visual display device of the present invention will be described below. In addition,
The surface shapes of the reflecting surface and the refracting surface in each example are as follows: paraxial radius of curvature is _Rx , radius of curvature in XZ plane (plane perpendicular to the paper), and curvature in YZ plane. When the radius is R _y , it is expressed by the following equation.

Z = [(X ² / R _x ) + (Y ² / R _y )] ÷ [1+ {1- (1 + K _x ) (X ² / R _x ² ) − (1 + K _y ) (Y ² / R _y ² )} ^1/2 ] + AR [(1-AP) X ² + (1 + AP) Y ² ] ² + BR [(1-BP) X ² + (1 + BP) Y ² ] ³ where K _x is the X direction. The conical coefficient of K, K _y is the conical coefficient in the Y direction, AR and BR are rotationally symmetric fourth-order and sixth-order aspherical coefficients, AP and BP are non-rotationally symmetric fourth-order, respectively.
The following aspherical coefficients. When the surface shape is rotationally symmetric, R _x , K _x , AP and BP are not particularly displayed. Also,
When the surface shape is spherical, K _x , K _y , AR, BR, A
P and BP are not particularly displayed.

Example 1 An eyepiece optical system of Example 1 will be described with reference to FIG. In the figure, 1 is a two-dimensional image display device, 2 is a first reflecting surface, 3 is a second reflecting surface, 4 is a viewer pupil position, and 15 is a visual axis when the viewer is observing the front. is there. In the case of this embodiment, the first reflecting surface 2 is a plane mirror and the second reflecting surface 3 is a concave mirror having power. As shown in the figure, the coordinate system is an X-axis whose right to left is a positive direction in the left-right direction of the observer, and Z is a positive direction from the eyeball side of the observer's visual axis 15 direction to the second reflecting surface 3 side. The axis is defined as the Y axis that extends from the bottom to the top in the vertical direction.

The constituent parameters of this optical system are shown below, but the surface number is shown as the surface number of the backward tracking from the observer pupil position 4 to the two-dimensional image display element 1. For the second reflecting surface 3 (surface number: 2), the eccentricity amount and the tilt angle are
Only the tilt angle of the central axis passing through the apex of the surface from the Z-axis direction is given, and with respect to the first reflecting surface 2 (surface number: 3), the Y-axis negative from the center of the observer pupil 4 at the apex of the surface is given. Direction and Z
Amount of eccentricity in the positive direction of the axis and Z of the central axis passing through the apex of the surface
The tilt angle from the axial direction is given. Further, regarding the two-dimensional image display element 1 (plane number: 4), the eccentric amount in the Y-axis positive direction and the Z-axis positive direction from the center of the observer's pupil 4 at the center, and the normal line Z of the plane. The tilt angle from the axial direction is given. Regarding the tilt angle, the rotation angle (counterclockwise in the figure) from the Z-axis positive direction to the Y-axis positive direction is the positive rotation angle.

As for the surface spacing, the distance between the observer pupil 4 and the second reflecting surface 3 is the center of the observer pupil 4 and the second reflecting surface 3.
In the Z-axis direction. The sign of the radius of curvature is positive when the ray is traced backwards from the observer's pupil 4 when the surface shape has a convex surface in the traveling direction of the light ray, and the surface shape has a concave surface in the traveling direction of the light ray. If negative, it is negative.

Surface Number Curvature Radius Interval Spacing Eccentricity Tilt Angle 1 (4) ∞ (Pupil) 56.00 2 (3) R _y -112.00 0.00 22.5 ° R _x -96.16 (Reflecting Surface) 3 (2) ∞ 0.00 Y:- 16.00 67.5 ° (Reflecting surface) Z: 40.00 4 (1) ∞ Y: 13.38 90.0 ° (Image display element) Z: 40.00 The angle of view in the above embodiment is 30 ° in left and right angles and 1 in vertical angle of view.
At 2 °, the pupil diameter is 6 mm, the focal length is 56 mm, and the F number is 9.3.

A spot diagram showing the aberration correction state of this embodiment is shown in FIG. In FIG. 24, among the four numbers on the left side of the spot diagram, the two numbers in the upper row indicate the coordinates (X, Y) at the center of the rectangular screen ((0.0, Y)).
0, 0.00), and the coordinates of the center of the right end are (0, 00, -1.
00), the coordinates of the upper right corner are expressed as (1.00, -1.00), and the coordinates of the center of the upper end are expressed as (1.00, 0.00), the coordinates (X, Y) are shown. The two numbers are
The X and Y components (in degrees) of the angle formed by the coordinate (X, Y) direction with respect to the visual axis (center of the screen) are shown.

Example 2 An eyepiece optical system of Example 2 will be described with reference to FIG. In the figure, 1 is a two-dimensional image display device, 2 is a first reflecting surface, 3 is a second reflecting surface, 4 is a viewer pupil position, and 15 is a visual axis when the viewer is observing the front. is there. The structure of this embodiment is basically the same as that of the first embodiment, but the first reflecting surface 2 is a concave mirror having power.

The constituent parameters of this optical system are shown below, but the surface number is shown as the surface number of the backward tracking from the position of the observer's pupil 4 toward the two-dimensional image display element 1. The method of setting the coordinate system and the method of giving the amount of eccentricity and the tilt angle are the same as in the first embodiment. The method of displaying the surface distance between the observer pupil 4 and the second reflecting surface 3 and the sign of the radius of curvature are also the same as in the first embodiment.

Surface number Curvature radius Spacing Decentering amount Inclination angle 1 (4) ∞ (pupil) 60.00 2 (3) R _y -169.44 0.00 22.5 ° (reflection surface) 3 (2) R _y -252.40 0.00 Y: -20.00 67.5 ° R _x -142.35 Z: 40.00 (Reflecting surface) 4 (1) ∞ Y: 15.00 81.73 ° (Image display device) Z: 40.00 1
At 8 °, the pupil diameter is 10 mm, the focal length is 56 mm, and the F number is 5.6. FIG. 24 showing the aberration correction state of this example.
A spot diagram similar to that is shown in FIG.

Example 3 An eyepiece optical system of Example 3 will be described with reference to FIG. In the figure, 1 is a two-dimensional image display device, 10 is a refracting surface of a rear surface mirror 9 having a first reflecting surface 2, 2 is a first reflecting surface, 3 is a second reflecting surface, and 4 is an observer pupil position. , 15 are visual axes when the observer is observing the front. The configuration of this embodiment is basically the same as that of the second embodiment, but the first reflecting surface 2 is configured as a back surface mirror 9.

The constituent parameters of this optical system are shown below, but the surface number is shown as the surface number of the backward tracking from the position of the observer's pupil 4 toward the two-dimensional image display element 1. The method of setting the coordinate system and the method of giving the eccentricity amount and the tilt angle are the same as in the first embodiment.
The decentering amount and the tilt angle of the refracting surface 10 of the back surface mirror 9 are the same as those of the reflecting surface 2 of the back surface mirror 9. The method of displaying the surface distance between the observer pupil 4 and the second reflecting surface 3 and the sign of the radius of curvature are also the same as in the first embodiment.

The glass material forming the rear surface mirror has a refractive index of 1.516 and an Abbe number of 64.1. Surface number Curvature radius Spacing Eccentricity Tilt angle 1 (4) ∞ (pupil) 60.00 2 (3) R _y -157.56 0.00 22.5 ° (Reflective surface) 3 (10) R _y -126.99 0.00 Y: -16.56 66.3 ° R _x -71.39 Z: 40.00 (refractive surface) 4 (2) R _y -201.47 0.00 Y: -22.00 67.5 ° K _y 0 Z: 40.00 AR -0.1261 × 10 ^-6 BR -0.4054 × 10 ^-14 R _x -114.93 K _x 0 AP -0.1549 BP 0.2948 × 10 ² (Reflecting surface) 5 (10) R _y -126.99 0.00 Y: -16.56 66.3 ° R _x -71.39 Z: 40.00 (Refracting surface) 6 (1) ∞ Y: 14.87 90.00 ° (Image display device) Z: 40.00 Regarding the angle of view of the above embodiment, the horizontal angle of view is 30 ° and the vertical angle of view is 2
At 0 °, the pupil diameter is 10 mm, the focal length is 56 mm, and the F number is 5.6. FIG. 24 showing the aberration correction state of this example.
A spot diagram similar to that is shown in FIG.

Example 4 An eyepiece optical system of Example 4 will be described with reference to FIG. In the figure, 1 is a two-dimensional image display device, 10 is a refracting surface of a rear surface mirror 9 having a first reflecting surface 2, 2 is a first reflecting surface, 17
Is the refracting surface of the backside mirror 16 having the second reflecting surface 3, and 3 is the second
, 4 is the observer's pupil position, and 15 is the visual axis when the observer is observing the front. The configuration of this embodiment is basically the same as that of the third embodiment, but the second reflecting surface 3 is also configured as the back mirror 16.

The constituent parameters of this optical system are shown below, but the surface number is shown as the surface number of the backward tracking from the position of the observer's pupil 4 toward the two-dimensional image display element 1. The method of setting the coordinate system and the method of giving the eccentricity amount and the tilt angle are the same as in the first embodiment.
The decentering amount and tilt angle of the refracting surface 10 of the back surface mirror 9 are the same as those of the reflecting surface 2 of the back surface mirror 9, and the decentering amount and tilt angle of the refracting surface 17 of the back surface mirror 16 are similar to those of the back surface mirror 16. Similar to surface 3. The method of displaying the surface distance between the observer pupil 4 and the refracting surface 17 of the back mirror 16 having the second reflecting surface 3 is also the same as in the first embodiment. Rear surface mirror 16 having second reflecting surface 3
The surface distance between the refracting surface 17 and the second reflecting surface 3 is in the Z-axis direction. The signs of the radius of curvature are also the same as in the first embodiment.

The refractive index of the glass material forming each rear surface mirror is 1.516, and the Abbe number is 64.1. Surface number Curvature radius Spacing Eccentricity Tilt angle 1 (4) ∞ (pupil) 56.02 2 (17) R _y -95.84 6.53 22.0 ° R _x 171.18 (refractive surface) 3 (3) R _y -158.47 -6.53 21.6 ° K _y 0 AR -0.2545 × 10 ^-7 R _x -550.81 K _x 0 AP 0.7020 (Reflecting surface) 4 (17) R _y -95.84 0.00 22.0 ° R _x 171.18 (Refracting surface) 5 (10) R _y -75.35 0.00 Y : -21.80 65.6 ° R _x -161.42 Z: 35.00 (refractive surface) 6 (2) R _y -124.51 0.00 Y: -27.00 67.5 ° K _y 0 Z: 35.00 AR 0.8244 × 10 ^-10 R _x -235.30 K _x 0 AP -0.2322 × 10 ² (Reflecting surface) 7 (10) R _y -75.35 0.00 Y: -21.80 65.6 ° R _x -161.42 Z: 35.00 (Refractive surface) 8 (1) ∞ Y: 15.67 90.0 ° (Image display device) ) Z: 35.00 The angle of view in the above embodiment is 30 ° in the horizontal angle of view and 2 in the vertical angle of view.
At 3 °, the pupil diameter is 10 mm, the focal length is 58 mm, and the F number is 5.8. FIG. 24 showing the aberration correction state of this example.
A spot diagram similar to that is shown in FIG.

Example 5 An eyepiece optical system of Example 5 will be described with reference to FIG. In the figure, 1 is a two-dimensional image display element, among the components of the prism 7, 5 is a first refracting surface, 2 is a first reflecting surface, 3 is a second reflecting surface, and 6 is a second refracting surface. 4 is the observer pupil position,
Reference numeral 15 is a visual axis when the observer is observing the front.
This embodiment is an example in which a prism 7 including two reflecting surfaces 2 and 3 and two transmitting surfaces (refractive surfaces) 5 and 6 is used in the eyepiece optical system.

The constituent parameters of this optical system are shown below, but the surface number is shown as the surface number of the backward tracking from the position of the observer's pupil 4 toward the two-dimensional image display element 1. The coordinate system is the same as in the first embodiment.

The surface spacing is indicated by the distance along the axial principal ray (optical axis) from the intersection of the surface and the optical axis to the intersection of the surface of the next surface and the optical axis. Further, the tilt angle indicates an angle formed by a straight line perpendicular to the optical axis passing through the intersection of the surface and the optical axis and a tangent line of the surface passing through the intersection of the surface and the optical axis. The tilt angle is negative if the tilt of the tangent to the surface passing through the intersection of the surface and the optical axis is clockwise from the straight line perpendicular to the optical axis passing through the intersection of the surface and the optical axis, and may be counterclockwise. Show as positive.

The sign of the radius of curvature is positive when the ray is traced backwards from the observer's pupil 4 when the surface shape is convex in the traveling direction of the ray, and the surface shape is in the traveling direction of the ray. Negative when facing the concave surface.

Surface number Curvature radius Spacing Refractive index Abbe number Tilt angle 1 (4) ∞ (pupil) 20.00 2 (6) R _y 36.82 23.00 1.516 64.1 (refractive surface) 3 (3) R _y -451.43 18.00 1.516 64.1 22.5 ° (Reflecting surface) 4 (2) R _y -332.85 22.00 1.516 64.1 22.5 ° (Reflecting surface) 5 (5) R _y -174.72 7.00 (Refractive surface) 6 (1) ∞ (Image display element) Angle of view of the above embodiment Has a horizontal angle of view of 20 ° and a vertical angle of view of 2
At 0 °, the pupil diameter is 8 mm, the focal length is 40 mm, and the F number is 5.0. A spot diagram showing the aberration correction state of Example 5 is shown in FIG. In FIG. 28, among the four numbers on the left side of the spot diagram, the two numbers in the upper row indicate the coordinates (X, Y) at the center of the rectangular screen (0.0
0,0.00), the coordinates of the center of the left end are (1.00,0.0
0), the coordinates of the upper left corner are expressed as (1.00, 1.00), and the coordinates of the center of the upper end are expressed as (0.00, 1.00), indicating the coordinates (X, Y). Two numbers indicate the X component and the Y component (in degrees) of the angle formed by the coordinate (X, Y) direction with respect to the visual axis (center of the screen) (the display method of the coordinates is different from the first to fourth embodiments). Note that).

Example 6 An eyepiece optical system of Example 6 will be described with reference to FIG. In the figure, 1 is a two-dimensional image display element, among the components of the prism 7, 5 is a first refracting surface, 2 is a first reflecting surface, 3 is a second reflecting surface, and 6 is a second refracting surface. 4 is the observer pupil position,
Reference numeral 15 is a visual axis when the observer is observing the front.
In this embodiment, the first refracting surface 5 forming the prism 7 has a rotationally symmetric aspherical shape in order to more favorably correct the rotationally symmetric field curvature. Further, the two-dimensional image display element 1 is arranged so as to be tilted in order to better correct the tilt of the image plane caused by the reflecting surface decentered with respect to the optical axis forming the prism 7. .

The constituent parameters of this optical system are shown below, but the surface number is shown as the surface number of the backward tracking from the position of the observer's pupil 4 toward the two-dimensional image display element 1. Coordinate system,
The definitions of the surface spacing, the inclination angle, and the sign of the radius of curvature are the same as in the fifth embodiment.

Surface number Curvature radius Spacing Refractive index Abbe number Tilt angle 1 (4) ∞ (pupil) 20.00 2 (6) R _y 36.96 26.00 1.516 64.1 (refractive surface) 3 (3) R _y ∞ 20.00 1.516 64.1 22.5 ° ( (Reflecting surface) 4 (2) R _y -401.75 25.00 1.516 64.1 22.5 ° (Reflecting surface) 5 (5) R _y -21.19 10.78 K _y 0.00 AR 0.76204 × 10 ^-4 BR -0.40793 × 10 ^-7 (Refractive surface) 6 (1) ∞ -4.9 ° (image display element) The angle of view of the above embodiment is 20 ° in the left and right angles and 2 in the up and down angles of view.
At 0 °, the pupil diameter is 8 mm, the focal length is 40 mm, and the F number is 5.0. FIG. 28 showing the aberration correction state of this example.
A spot diagram similar to that is shown in FIG.

Example 7 An eyepiece optical system of Example 7 will be described with reference to FIG. In the figure, 1 is a two-dimensional image display element, among the components of the prism 7, 5 is a first refracting surface, 2 is a first reflecting surface, 3 is a second reflecting surface, and 6 is a second refracting surface. 4 is the observer pupil position,
Reference numeral 15 is a visual axis when the observer is observing the front.
In this embodiment, the second reflecting surface 3 that constitutes the prism 7 is used.
Is a surface having different radii of curvature in the spherical surface and the meridian surface. Both the spherical surface and the meridian surface are spherical. The rotationally symmetric field curvature is corrected by making the first refracting surface 5 forming the prism 7 a rotationally symmetric aspherical surface.

The constituent parameters of this optical system are shown below, but the surface number is shown as the surface number for the backward tracking from the position of the observer's pupil 4 toward the two-dimensional image display element 1. Coordinate system,
The definitions of the surface spacing, the inclination angle, and the sign of the radius of curvature are the same as in the fifth embodiment.

Surface number Curvature radius Spacing Refractive index Abbe number Tilt angle 1 (4) ∞ (pupil) 20.00 2 (6) R _y 49.66 27.00 1.516 64.1 (refractive surface) 3 (3) R _y -365.45 21.00 1.516 64.1 22.5 ° R _x -293.36 (Reflecting surface) 4 (2) R _y -351.05 26.00 1.516 64.1 22.5 ° (Reflecting surface) 5 (5) R _y -35.72 6.67 K _y 0.00 AR 0.59957 × 10 ^-4 (Refractive surface) 6 (1 ) ∞ (Image display element) The angle of view in the above embodiment is 20 ° in the horizontal angle of view and 2 in the vertical angle of view.
At 4 °, the pupil diameter is 8 mm, the focal length is 40 mm, and the F number is 5.0. FIG. 28 showing the aberration correction state of this example.
A spot diagram similar to that is shown in FIG.

Example 8 An eyepiece optical system of Example 8 will be described with reference to FIG. In the figure, 1 is a two-dimensional image display element, among the components of the prism 7, 5 is a first refracting surface, 2 is a first reflecting surface, 3 is a second reflecting surface, and 6 is a second refracting surface. 4 is the observer pupil position,
Reference numeral 15 is a visual axis when the observer is observing the front.
In this embodiment, the first reflecting surface 2 forming the prism 7 is formed of a toroidal surface, and the first refracting surface 5 forming the prism 7 is formed into a non-rotationally symmetric spherical shape. The point difference and the non-rotationally symmetric field curvature are reduced.

The constituent parameters of this optical system are shown below, but the surface number is shown as the surface number of the backward tracking from the position of the observer's pupil 4 toward the two-dimensional image display element 1. Coordinate system,
The definitions of the surface spacing, the inclination angle, and the sign of the radius of curvature are the same as in the fifth embodiment.

Surface number Curvature radius Spacing Refractive index Abbe number Tilt angle 1 (4) ∞ (pupil) 20.00 2 (6) R _y 64.84 32.00 1.516 64.1 (refractive surface) 3 (3) R _y -257.07 24.50 1.516 64.1 22.5 ° (Reflecting surface) 4 (2) R _y -342.05 31.00 1.516 64.1 22.5 ° K _y 0.00 AR 0.34422 × 10 ^-6 BR 0.56290 × 10 ^-10 R _x -201.94 (Reflecting surface) 5 (5) R _y 110.83 2.10 R _x 464.13 (Refractive surface) 6 (1) ∞ (Image display element) Regarding the angle of view of the above embodiment, the horizontal angle of view is 20 ° and the vertical angle of view is 3
At 0 °, the pupil diameter is 8 mm, the focal length is 45 mm, and the F number is 5.625. FIG. 31 shows a spot diagram similar to FIG. 28 showing the aberration correction state of this embodiment.

Example 9 An eyepiece optical system of Example 9 will be described with reference to FIG. In the figure, 1 is a two-dimensional image display element, among the components of the prism 7, 5 is a first refracting surface, 2 is a first reflecting surface, 3 is a second reflecting surface, and 6 is a second refracting surface. 4 is the observer pupil position,
Reference numeral 15 is a visual axis when the observer is observing the front.
In this embodiment, the first reflecting surface 2 constituting the prism 7 is formed of an anamorphic aspherical surface, and the second reflecting surface 3 is formed into a non-rotationally symmetric spherical surface, thereby further reducing the astigmatic difference. The rotationally symmetric field curvature is reduced. Further, since the first reflecting surface 2 having the anamorphic aspherical shape has a large aberration correcting ability, the decentering amount of the first reflecting surface 2 is increased, while the second reflecting surface 2 having a relatively small aberration correcting ability is provided. The amount of eccentricity of the reflecting surface 3 is reduced.

Hereinafter, the constituent parameters of this optical system will be shown. The surface number is shown as the surface number of the backward tracking from the position of the observer's pupil 4 toward the two-dimensional image display element 1. Coordinate system,
The definitions of the surface spacing, the inclination angle, and the sign of the radius of curvature are the same as in the fifth embodiment.

Surface number Curvature radius Spacing Refractive index Abbe number Tilt angle 1 (4) ∞ (pupil) 20.00 2 (6) R _y 68.34 36.00 1.516 64.1 (refractive surface) 3 (3) R _y -228.02 25.50 1.516 64.1 21.0 ° R _x -220.73 (Reflecting surface) 4 (2) R _y -382.62 29.00 1.516 64.1 28.0 ° K _y 0.00 AR 0.42629 × 10 ^-6 BR -0.80021 × 10 ^-10 R _x -210.77 K _x 0.00 AP 0.10975 (Reflecting surface) 5 (5) R _y 129.15 2.15 (Refractive surface) 6 (1) ∞ (Image display element) The angle of view of the above embodiment is 20 ° in the left and right angles and 3 in the vertical angle of view.
At 0 °, the pupil diameter is 8 mm, the focal length is 45 mm, and the F number is 5.625. FIG. 32 shows a spot diagram similar to FIG. 28 showing the aberration correction state of this example.

Example 10 An eyepiece optical system of Example 10 will be described with reference to FIG. In the figure, 1 is a two-dimensional image display device, 27 is the concave surface of a concave lens that constitutes the doublet 26, and 28 is the doublet 26.
Of the components of the prism 7, 5 is a first refracting surface, 2 is a first reflecting surface, 3 is a second reflecting surface, and 6 is a second reflecting surface. 2 is a refracting surface, 4 is an observer's pupil position, and 15 is a visual axis when the observer is observing the front. In this embodiment, the prism 7
In order to correct the chromatic aberration that occurs on the refracting surface of No. 2, the doublet 26 for chromatic aberration correction is arranged in the eyepiece optical system, and it has succeeded in obtaining a clearer observation image.

The constituent parameters of this optical system are shown below, but the surface number is shown as the surface number of the backward tracking from the position of the observer's pupil 4 toward the two-dimensional image display element 1. Coordinate system,
The definitions of the surface spacing, the inclination angle, and the sign of the radius of curvature are the same as in the fifth embodiment.

Surface number Curvature radius Spacing Refractive index Abbe number Tilt angle 1 (4) ∞ (pupil) 20.00 2 (6) R _y 6186.53 45.00 1.516 64.1 (refractive surface) 3 (3) R _y -1397.29 33.00 1.516 64.1 22.5 ° _Rx -706.09 (Reflecting surface) 4 (2) _Ry -382.32 40.00 1.516 64.1 22.5 ° _Rx -414.61 (Reflecting surface) 5 (5) _Ry -94.91 2.75 (Refractive surface) 6 (19) _Ry 39.36 17.35 1.744 44.7 7 (18) R _y -47.82 7.66 1.745 28.0 8 (17) R _y 30.02 12.89 9 (1) ∞ -3.5 ° (Image display element) The angle of view of the above embodiment is 30 ° in the left and right, and in the vertical direction. Angle of view is 2
At 2.5 °, the pupil diameter is 7 mm, the focal length is 53 mm, and the F number is 6.63. FIG. 33 shows a spot diagram similar to FIG. 28 showing the aberration correction state of this example.

As described above, in the first to tenth embodiments, all the constituent elements of the eyepiece optical system have been treated as the reflecting surface or the refracting surface. However, by making the second reflecting surface a semi-transmissive surface, the eyepiece optical system It is possible to give the system a superimpose function. Further, in Examples 1 to 10, the X axis is the horizontal direction and the Y axis is the vertical direction, but the X axis is the vertical direction.
It goes without saying that the Y axis can be handled as the left-right direction.

The visual display device of the present invention described above can be configured as follows, for example. [1] In a visual display device including a two-dimensional image display element for displaying an observation image and an eyepiece optical system for forming an eye point for guiding the observation image to an observer's eyeball, the eyepiece optical system is at least a first one. And a second reflecting surface, the first reflecting surface is arranged to face the two-dimensional image display element, and the second reflecting surface faces the eye point. The optical axis connecting the first reflecting surface and the two-dimensional image display element is arranged to intersect with the optical axis connecting the second reflecting surface and the eye point. A visual display device characterized by.

[2] A visual display device comprising a two-dimensional image display element for displaying an observation image and an eyepiece optical system for forming an eyepoint for guiding the observation image to the observer's eyeball. At least a first reflective surface and a second
A prism having a reflective surface, a first transmissive surface and a second transmissive surface, wherein the prism has a two-dimensional image display device with the first reflective surface interposed therebetween. Light that is disposed so as to face the eye point with the second reflective surface interposed therebetween and the second transmissive surface is interposed therebetween, and connects the first reflective surface and the first transmissive surface. The visual display device is arranged such that an axis, an optical axis connecting the second reflecting surface and the second transmitting surface intersect with each other.

[3] In a visual display device comprising a two-dimensional image display element for displaying an observation image and an eyepiece optical system for forming an eye point for guiding the observation image to an observer's eyeball, the eyepiece optical system is At least a first reflective surface and a second
And a second reflecting surface, and the optical axes passing through the first reflecting surface and the second reflecting surface partially intersect each other to form a polygon. Visual display device.

[4] At least one of the first reflecting surface and the second reflecting surface has a positive power, and the above-mentioned [1] to [3]. Visual display device.

[5] The above-mentioned [1], wherein both the first reflecting surface and the second reflecting surface have positive power.
To The visual display device according to any one of [3].

[6] At least one of the first reflective surface and the second reflective surface includes a transmissive surface on the reflective surface side, and a medium having an arbitrary refractive index is sandwiched between the reflective surfaces. The visual display device according to any one of [1] to [3] above, which is a rear surface mirror.

[7] At least one of the first reflecting surface and the second reflecting surface has a concave shape, and the concave surface is based on the intersection of the reflecting surface and the optical axis. Compared with the radius of curvature of the reflecting surface in a plane including both the optical axis and a normal line passing through the intersection, the radius of curvature of the reflecting surface in a plane perpendicular to the plane including the intersection may be different. Any one of the above-mentioned [1] to [3]
The visual display device according to the item.

[8] At least one of the transmissive surfaces has at least one transmissive surface having a curved surface shape, and the curved surface has the optical axis and the intersection point with the intersection point of the transmissive surface and the optical axis as a reference. The radius of curvature of the transmission surface in the plane including the intersection and perpendicular to the plane is different from the radius of curvature of the transmission surface in the plane including both the normal line passing through. ] Or the visual display device according to [6].

[0112]

[9] In order to have a superimpose function capable of simultaneously transmitting an observation image from the two-dimensional image display device and natural light from the outside to the eye point, the first reflection surface and the second reflection surface are The visual display device according to any one of the above [1] to [8], wherein at least one of the reflecting surfaces is a semi-transmissive surface.

[10] 20% or more of the semi-transmissive surface is 80
%, The transmittance is less than or equal to

[9] The visual display device as described above.

[0114]

As is apparent from the above description, according to the present invention, the overall size is compact, the decrease in the amount of light in the eyepiece optical system is small, and the wide angle of view is clear in every corner of the observed image. The visual display device can be provided.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an arrangement of reflecting surfaces that constitute a visual display device of the present invention.

FIG. 2 is a cross-sectional view showing the arrangement of reflective surfaces of a similar visual display device of the prior art.

FIG. 3 is a cross-sectional view showing a configuration of a visual display device of the present invention using a prism.

FIG. 4 is a conceptual diagram for explaining the operation of the visual display device of the present invention.

5 is a cross-sectional view for explaining one modification of the visual display device of FIG.

FIG. 6 is a conceptual diagram for explaining the operation of the visual display device of FIG.

FIG. 7 is a cross-sectional view when the reflecting surface of the visual display device of FIG. 1 is configured by one rear surface mirror.

FIG. 8 is a three-dimensional view showing light rays when the reflecting surface of the eyepiece optical system is rotationally symmetrical.

FIG. 9 is a three-dimensional view showing rays of light when the reflecting surface of the eyepiece optical system is non-rotationally symmetric.

10 is a sectional view for explaining another modification of the visual display device of FIG.

FIG. 11 is a diagram showing a means for dividing the transmitted and reflected light amounts by area.

FIG. 12 is a diagram showing means for dividing the transmitted and reflected light amounts in terms of light amount.

FIG. 13 is a diagram showing a unit that divides a transmitted light amount and a reflected light amount according to polarized light.

FIG. 14 is a cross-sectional view showing an optical configuration of Example 1.

FIG. 15 is a sectional view showing an optical configuration of Example 2.

FIG. 16 is a cross-sectional view showing an optical configuration of Example 3.

FIG. 17 is a sectional view showing an optical configuration of Example 4.

FIG. 18 is a sectional view showing an optical configuration of Example 5;

FIG. 19 is a sectional view showing the optical configuration of Example 6;

20 is a sectional view showing the optical configuration of Example 7. FIG.

21 is a sectional view showing the optical configuration of Example 8. FIG.

22 is a sectional view showing the optical configuration of Example 9. FIG.

23 is a sectional view showing the optical configuration of Example 10. FIG.

FIG. 24 is a spot diagram showing an aberration correction state of Example 1.

FIG. 25 is a spot diagram showing an aberration correction state of Example 2.

FIG. 26 is a spot diagram showing the aberration correction state of Example 3;

FIG. 27 is a spot diagram showing the aberration correction state of Example 4.

FIG. 28 is a spot diagram showing the aberration correction state of Example 5;

FIG. 29 is a spot diagram showing the aberration correction state of Example 6;

FIG. 30 is a spot diagram showing the aberration correction state of Example 7.

31 is a spot diagram showing the aberration correction state of Example 8. FIG.

FIG. 32 is a spot diagram showing the aberration correction state of Example 9;

FIG. 33 is a spot diagram showing the aberration correction state of Example 10.

FIG. 34 is a cross-sectional view showing one prior art optical configuration.

FIG. 35 is a cross-sectional view showing another conventional optical configuration.

FIG. 36 is a cross-sectional view showing another conventional optical configuration.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Two-dimensional image display element 2 ... 1st reflective surface 3 ... 2nd reflective surface 4 ... Viewer's pupil position 5 ... 1st transmissive surface 6 ... 2nd transmissive surface 7 ... Prism 8 ... 2D image Inclination position 9 of display element ... Rear surface mirror 10 having first reflecting surface ... Refractive surface 15 of rear surface mirror ... Visual axis 16 when observer observes front surface ... Rear surface mirror 17 having second reflecting surface Refractive surface 26 of back-side mirror ... Doublet 27 ... Concave surface 28 of concave lens forming doublet ... Joining surface 29 of doublet ... Convex surface 41 of convex lens forming doublet ... Transparent substrate 42 ... Aluminum coating 43 ... Semitransparent thin film 44 ... Polarizing property Semi-transmissive thin film Z ... Visual axis Z ₁ when an observer is observing the front surface ... Perpendicular to the first reflecting surface Z ₂ ... Perpendicular to the second reflecting surface L _CR ... Luminous flux L _MR consisting of chief ray ... upper and off-axis light flux F ₀ ... front focal point F ₁ ... rear focal point position f ... optical system Focal length f ₁ ... focal length f ₂ ... second focal length of the reflecting surface of ff1 ... front focal length bf1 ... rear focal length d ... first reflecting surface and the distance of the second reflecting surface of the first reflecting surface H, H _1, H ₂ ... principal point O of the optical system, O ₂ ... intersection L _UP ... observer's pupil and the second reflecting surface and the intersection O ₁ ... first reflecting surface of the optical axis and the optical axis from the upper off-axis light beam L _LOW ... viewer lower off-axis light beam L ... imaging plane I _Y ... meridional image of the axial light flux I _X ... Tamaketsuzo viewed from the observer's pupil as seen from the pupil of viewed Image plane

─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A 4-170512 (JP, A) JP-A 5-154106 (JP, A) JP-A 63-264701 (JP, A) JP-A 54- 14253 (JP, A) JP 58-78116 (JP, A) Actual development 55-113520 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G02B 25/00 G02B 5 / 04 G02B 17/00 G03B 13/00

Claims (8)

(57) [Claims] 1. A visual display device comprising a two-dimensional image display element for displaying an observation image and an eyepiece optical system for forming an eye point for guiding the observation image to an observer's eyeball, wherein the eyepiece optical system is at least It has a 1st reflective surface and a 2nd reflective surface, the said 1st reflective surface is arrange | positioned so as to oppose the said two-dimensional image display element, and the said 2nd reflective surface opposes the said eyepoint. And an optical axis connecting the first reflecting surface and the two-dimensional image display element intersects an optical axis connecting the second reflecting surface and the eye point. And both the first reflecting surface and the second reflecting surface have positive power.
And, at least one shape in the reflective surface, in the sagittal plane
Make the power stronger than the positive power in the meridian plane and
A visual display device characterized in that the focal length of the luminous flux of is shortened . 2. A visual display device comprising a two-dimensional image display element for displaying an observation image and an eyepiece optical system for forming an eye point for guiding the observation image to an observer's eyeball, wherein the eyepiece optical system is at least A prism having a first reflective surface, a second reflective surface, a first transmissive surface and a second transmissive surface, wherein the prism has the first transmissive surface in between. Is disposed to face the two-dimensional image display element, the second reflective surface is disposed to face the eye point with the second transmissive surface interposed therebetween, and the first reflective surface and the first reflective surface are disposed. The optical axis connecting the first transmitting surface and the optical axis connecting the second reflecting surface and the second transmitting surface are arranged so as to intersect with each other, and the first reflecting surface or the second reflecting surface. At least one of the faces
The reflecting surface has a positive power, and the first reflecting surface, the second reflecting surface, and the first transmitting surface.
A surface, at least one shape in the second transparent surface is
The power in the sagittal plane is stronger than the positive power in the meridian plane
However, the focal length of the light flux in the spherical surface is shortened.
Visual display apparatus characterized by being. 3. A visual display device comprising a two-dimensional image display element for displaying an observation image and an eyepiece optical system for forming an eyepoint for guiding the observation image to an observer's eyeball, wherein the eyepiece optical system is at least A first reflecting surface and a second reflecting surface are arranged, and the optical axes passing through the first reflecting surface and the second reflecting surface are partially intersected to form a polygon. are, have the first and second reflective surfaces are positive power
And, at least one shape in the reflective surface, in the sagittal plane
Make the power stronger than the positive power in the meridian plane and
A visual display device characterized in that the focal length of the luminous flux of is shortened . 4. The visual display device according to claim 2, wherein both the first reflecting surface and the second reflecting surface have positive power. 5. At least one of the first reflecting surface and the second reflecting surface includes a transmitting surface on the reflecting surface side, and a medium having an arbitrary refractive index is sandwiched between the reflecting surface and the transmitting surface. The visual display device according to claim 1 , wherein the visual display device is a rear surface mirror. 6. At least one transmissive surface of at least one of the transmissive surfaces has a curved surface shape, and the curved surface defines the optical axis and the intersecting point with reference to the intersecting point of the transmissive surface and the optical axis. The radius of curvature of the transmission surface in a plane including the intersection and perpendicular to the plane is different from the radius of curvature of the transmission surface in a plane including both normals passing therethrough. 5. The visual display device according to item 5 . 7. The first image display device has a superimpose function capable of simultaneously transmitting an observation image from the two-dimensional image display device and natural light from the outside to the eye point.
Claims 1, at least one reflecting surface in reflecting surface and the second reflective surface, comprising the semitransparent surface of the 6
The visual display device according to claim 1. 8. The visual display device according to claim 7, wherein the semi-transmissive surface has a transmittance of 20% or more and 80% or less.